Data Logging – What
It is now a requirement from the CAA to have a GPS data logger fitted to every over 25kg model aircraft. You have several options on how to log the data, either logged in the aircraft or sent back to the transmitter by telemetry for logging there.
What needs needs to be logged is in the Over 25kg design requirements-
DR‐LMA‐5400 Flight data recorder
The UAS must be fitted with a flight data recording system that must ensure accurate and intelligible recording of the GPS time/ date and the speed and 3‐dimensional position of the UA every 2 seconds.
Data Logging – How
Data can be logged onboard the aircraft with a standalone unit or in a Powerbox unit or similar if it will record the data and allow it to be extracted later.
Most radio manufacturers have GPS telemetry units that can send the data back to the transmitter, and most currently available transmitters can log to an SD card, but do check first.
Note that Powerbox GPS units will not work with Futaba radio as a telemetry sensor, not all the required GPS data will be available.
The logging device does not need to be permanently fitted to the aircraft, but every time the aircraft flies it must have the logger fitted and working.
Whatever solution you use, you must test that it is working and recording all the required information.
Standalone Data Loggers
Jet Accessories have for sale a very reasonably priced standalone fully compliant onboard data logger, available here.
RC Light Systems have for sale a very reasonably priced standalone fully compliant onboard data logger, available here.
Data Logging – DIY
If you fancy getting your hands slightly dirty, below are two examples of simple GPS units that just need a little bit of soldering. Examples of both of these units have been made, and it can be confirmed that they work and meet the minimum requirement.
Standalone GPS Data Logger
RC Groups Description Here
This uses a BN-220 GPS unit with a GY-Openlog data logger. It’s recommended to add a small voltage regulator (AMS1117-5.5V) to prevent any damage from a fully charged LiFe batery when the logger is plugged into a spare receiver port for power.
GPS Telemetry Unit
OpenX Sensor Description Here
This uses the same BN-220 GPS unit with a small Arduino loaded with he OpenX Sensor telemetry software. This allows the flight data to be seen and logged on the transmitter.
All the parts for both the units above can be found in the UK on AiiExpress, Banggood, eBay or Amazon.
Data Logging – Then What
Log Retention
There’s no specific requirement for how long logs need to be kept after each flight. As most solutions log to an SD card until full then overwrite the oldest log, the logs may as well be kept until overwritten.
The LMA will ask for logs to be provided from time to time as part of the LMA’s oversight of the over 25kg scheme.
Data Formats
The data just needs to be able to be extracted from where it is logged and analysed to give the minimum required data, it does not need to be in any specific format.